This invention relates to a milling and drilling head for a machine tool, and in particular for milling machines or NC machining centers incorporating magazines adapted to receive the individual tool bits.
On such machines, the tool holding spindle is generally controlled by a numerical control unit, and according to the types of work to be executed, tool bits aree picked up by means of a specially provided device, known per se, from a magazine as required for a specific cutting operation.
A distinct advantage of these modern machine tools is that the workpiece, once clamped to the table, may be subjected to multiple machining steps to be carried out automatically and by using a range of different tools, always under direct control by the NC unit and without intervention by the machine operator.
While the above-described machines, most of the cutting operations can be performed successfully using a single clamping of the workpiece to the table, it has not been possible, heretofore, to perform on these machines, with the aid of traditional tools, any operations under control by the NC unit which involved, for example, changes in the angle of the tool being employed relatively to the main spindle X-axis.
However, machining operations of this kind are a fairly frequent occurrence, e.g. to form holes and/or threads at different angular settings in cylindrical bodies coaxially with the spindle X-axis, or circumferential grooves in the outer or inner surfaces of cylindrical bodies, or S-like pattern grooves for the lubrication of rotary shafts, and the like. It has been necessary in the past to carry out such operations on some other cutting machines to complete the workpiece machining; which reflected in inferior machining precision and increased manufacturing costs, resulting in part from the need for special machine tools, often requiring the availability of some special tools and jigs, the high cost whereof is well recognized in the art.